1. Field of the Invention
The present invention relates to an object detecting system for a vehicle having a radar which includes an electromagnetic wave transmission means for transmitting an electromagnetic wave in a direction in which the vehicle is traveling and a reflected wave reception means for receiving an electromagnetic wave that is generated by objects in the direction of traveling of the vehicle reflecting the wave transmitted from the electromagnetic wave transmission means, whereby the system detects the objects based on the detection result of the radar.
2. Description of the Prior Art
A system has been known, as disclosed for example in Japanese Patent Application Laid-Open Nos. 8-240660 and 6-160510, which has a radar to transmit an electromagnetic wave such as a laser in a direction in which a vehicle is traveling and to receive an electromagnetic wave reflected from an object present in front of the vehicle, whereby the system detects the object in front of the vehicle based on the result of the search operation of the radar and, in accordance with the result of detection, issues an alarm to urge a driver to avoid the object by manual operation or automatically performs an object avoidance operation.
Such an object detecting system must detect only those objects present on the path in which the vehicle is traveling as path objects and avoid detecting or recognizing objects outside the path of travel. For this purpose, the conventional systems aim at improving the ability to detect path objects by setting the radar to have a plurality of horizontally differing detection directions or to scan in a horizontal direction and by estimating the direction of travel of the vehicle from the steering angle, yaw rate, and the like thereby to determine only those objects in the vehicle path as the path objects. Another means of improving the path object detection capability involves setting the radar to have a plurality of vertically differing detection directions or to scan in the vertical direction.
Although the detection direction of the radar is precisely adjusted before shipping, the detection direction may become misadjusted or deviated by light collision or other causes. When such a misadjustment or deviation is large, it becomes difficult to precisely locate the position of a path object, making it likely that the motion control of the vehicle with respect to the path object, will be inaccurate. It is therefore desirable that when the detection direction of the radar deviates, the misadjustment or deviation of the detection direction be automatically corrected or that the driver be informed and urged to make repairs.
To solve this problem, the object detection system disclosed in Japanese Patent Application Laid-Open No. 6-160510 detects the presence of a deviation in the radar detection direction based on a deviation of an observed locus of specific static objects, such as roadside reflectors, as observed from the vehicle with respect to a reference locus when traveling straight with a zero steering angle. This conventional system, however, can only detect the deviation in the detection direction under a limited condition, i.e., when the vehicle is traveling straight.